This invention relates to a liquid jetting apparatus having a head member capable of jetting liquid from nozzles, such as an ink-jet recording apparatus having a recording head capable of jetting ink from nozzles to form dots on a recording medium. In particular, this invention is related to a liquid jetting apparatus which can prevent viscosity of liquid in nozzles from increasing.
An ink-jet recording apparatus such as an ink-jet printer or an ink-jet plotter has a recording head that is movable along a main scanning direction. The recording head has nozzles capable of jetting ink. For example, the nozzles are communicated to pressure chambers which can expand and contract respectively. In the case, the ink in the nozzles can be jetted by expanding and contracting of the pressure chambers.
On the other hand, the ink-jet recording apparatus is adapted to feed a recording medium such as a paper along a subordinate scanning direction, which is perpendicular to the main scanning direction. Thus, the nozzles of the recording head can jet ink to form an image or a character on the recording medium in cooperation with moving the recording head and the recording medium according to recording data.
The ink in the nozzles of the recording head is exposed to air. Thus, solvent of the ink such as water may gradually evaporate to increase a viscosity of the ink in the nozzles. In the case, quality of printed (recorded) images may deteriorate because the ink having a great viscosity may be jetted toward a direction deviated from a normal direction.
To prevent the viscosity of the ink in the nozzles from increasing, some measures have been proposed. One of the measures is to cause a meniscus of the ink to minutely vibrate to stir the ink. The meniscus means a free surface of the ink exposed at an opening of the nozzle.
For stirring the ink, the meniscus may be vibrated to a jetting direction of the ink and to a contracting direction opposed to the jetting direction by turns in such a manner that the ink may not be jetted. The vibration of the meniscus can be also carried out by expanding and contracting of the pressure chambers. Owing to the vibration of the meniscus, the ink at the opening of the nozzle may be stirred to prevent the viscosity of the ink from increasing.
The stirring of the ink may be carried out during a recording operation. For example, the stirring may be carried out while a carriage carrying the recording head is being accelerated after starting a main scanning, or while a recording operation for a line is being carried out. In the stirring while the carriage is being accelerated, a micro-vibrating operating signal for micro vibrating is supplied to the recording head to cause all menisci in the nozzles to minutely vibrate. In the stirring while the recording operation is being carried out, a pulse signal for micro vibrating is generated from a jetting operating signal for jetting ink, and the pulse signal is supplied to the recording head. Thus, the ink in the nozzles not in the recording (jetting) operation may be stirred.
In addition, Japanese Patent Laid-Open Publication No. 2000-21507 has described that it is effective to cause menisci of ink in nozzles to minutely vibrate during a predetermined time from a suitable timing just before jetting a drop of the ink or from a suitable timing just before jetting a drop of the ink till another suitable timing just before jetting a drop of the ink.
Japanese Patent Laid-Open Publication No. 2000-21507 has also proposed a pre-printing micro-vibrating operation just before jetting a drop of the ink. In addition, Japanese Patent Laid-Open Publication No. 2000-21507 has disclosed that an out-of-printing micro-vibrating operation can be performed further before the pre-printing micro-vibrating operation.
However, if an ink whose viscosity tends to increase is used (for example, a kind of pigment ink or a kind of high-density dye ink), solvent of the ink may easily evaporate to increase a viscosity of the ink, even for a short time between a completion of a main scanning operation and a start of a next main scanning operation. In the case, it is possible that the state wherein the viscosity of the ink has been increased may not be dispelled sufficiently by means of the out-of-printing micro-vibrating operation or the pre-printing micro-vibrating operation after starting the next main scanning operation.
The object of this invention is to solve the above problems, that is, to provide a liquid jetting apparatus that can prevent a viscosity of liquid from increasing, even if a liquid whose viscosity tends to increase is used, such as an ink-jet recording apparatus.
In order to achieve the object, the invention is a liquid jetting apparatus comprising: a head member having a nozzle; a supporting member that can support a medium onto which liquid is to be jetted; a scanning mechanism that can cause the head member to relatively move with respect to the medium; a liquid jetting unit that can jet liquid from the nozzle; an area storing unit that stores a relative area to which liquid can be jetted from the nozzle while the head member is caused to relatively move by the scanning mechanism; an out-of-jetting micro-vibrating-area setting unit that can set out-of-jetting micro-vibrating areas before and after the relative area to which liquid can be jetted from the nozzle, based on the relative area to which liquid can be jetted from the nozzle; a scanning-position-information outputting unit capable of outputting head-position information that represents a relative position of the head member while the head member is caused to relatively move by the scanning mechanism; a micro-vibrating unit that can cause liquid in the nozzle to minutely vibrate; and an out-of-jetting micro-vibrating controlling unit that can cause the micro-vibrating unit to operate when the head member is located in the out-of-jetting micro-vibrating areas, while the head member is caused to relatively move by the scanning mechanism, based on the out-of-jetting micro-vibrating areas and the head-position information.
According to the above feature, since the out-of-jetting micro-vibrating areas are set before and after the relative area to which liquid can be jetted from the nozzle, it can be effectively prevented that a viscosity of the liquid increases between a completion of a scanning operation and a start of a next scanning operation.
Alternatively, the invention is a liquid jetting apparatus comprising: a head member having a nozzle; a supporting member that can support a medium onto which liquid is to be jetted; a scanning mechanism that can cause the head member to relatively move with respect to the medium; a liquid jetting unit that can jet liquid from the nozzle; an out-of-jetting micro-vibrating-area setting unit that can set out-of-jetting micro-vibrating areas before and after a liquid-jetting area to which liquid is to be jetted from the nozzle while the head member is caused to relatively move by the scanning mechanism, based on jetting data; a scanning-position-information outputting unit capable of outputting head-position information that represents a relative position of the head member while the head member is caused to relatively move by the scanning mechanism; a micro-vibrating unit that can cause liquid in the nozzle to minutely vibrate; and an out-of-jetting micro-vibrating controlling unit that can cause the micro-vibrating unit to operate when the head member is located in the out-of-jetting micro-vibrating areas, while the head member is caused to relatively move by the scanning mechanism, based on the out-of-jetting micro-vibrating areas and the head-position information.
According to the above feature, since the out-of-jetting micro-vibrating areas are set before and after the liquid-jetting area to which liquid is to be jetted from the nozzle while the head member is caused to relatively move by the scanning mechanism based on jetting data, it can be effectively prevented that a viscosity of the liquid increases between a completion of a scanning operation and a start of a next scanning operation.
The scanning mechanism may includes: a main-scanning mechanism that can cause the head member to relatively move with respect to the medium in a main scanning direction; and a sub-scanning mechanism that can cause the head member to relatively move with respect to the medium in a sub-scanning direction perpendicular to the main scanning direction. In the case, it is preferable that the out-of-jetting micro-vibrating-area setting unit includes: an actual-jetting-area calculating part that can obtain a jetting-starting position and a jetting-terminating position for each main scanning movement of the head member, based on jetting data; and an area-setting main part that can set out-of-jetting micro-vibrating areas based on the jetting-starting position and the jetting-terminating position. In the case, for example, the area-setting main part can set out-of-jetting micro-vibrating areas in such a manner that the out-of-jetting micro-vibrating areas are an area before the jetting-starting position and an area after the jetting-terminating position for each main scanning movement of the head member.
Alternatively, it is preferable that the out-of-jetting micro-vibrating-area setting unit further includes a second-area-setting main part that can set a pre-jetting micro-vibrating area based on the jetting-starting position, and that the area-setting main part is adapted to set out-of-jetting micro-vibrating areas in such a manner that the out-of-jetting micro-vibrating areas are an area before the pre-jetting micro-vibrating area and an area after the jetting-terminating position for each main scanning movement of the head member. In the case, the out-of-jetting micro-vibrating operation and the pre-jetting micro-vibrating operation can be separately controlled.
In addition, preferably, the out-of-jetting micro-vibrating controlling unit causes the micro-vibrating unit to operate from a completion of a main scanning movement of the head member to a start of a next main scanning movement thereof as well. That is, preferably, the out-of-jetting micro-vibrating operation can be performed during a sub-scanning movement as well. Thus, it can be prevented more surely that the viscosity of the liquid increases.
Herein, if liquid jetting operations are performed during both of two-way scanning movements i.e. forward and rearward scanning movements, it is preferable that the out-of-jetting micro-vibrating operation is suspended during a signal-switching operation for switching directions of the scanning movements.
That is, if a liquid-jetting controlling unit that can give a operating signal to the liquid jetting unit is provided, the scanning mechanism is adapted to cause the head member to relatively move with respect to the medium in forward and backward directions, and the liquid-jetting controlling unit is adapted to give a first operating signal to the liquid jetting unit while the head member is caused to relatively move with respect to the medium in a forward direction and to give a second operating signal to the liquid jetting unit while the head member is caused to relatively move with respect to the medium in a rearward direction, it is preferable that the out-of-jetting micro-vibrating controlling unit is adapted to cause the micro-vibrating unit to operate, from a completion of causing the head member to relatively move with respect to the medium in the forward direction until a start of switching operation of the operating signals by the liquid-jetting controlling unit and from a completion of the switching operation until a start of causing the head member to relatively move with respect to the medium in the rearward direction.
According to the above one or more features, compared to the conventional art, the out-of-jetting micro-vibrating operation is performed for a longer time. Thus, the micro-vibrating unit, for example a piezoelectric vibrating member such as PZT, may be deteriorated earlier.
Thus, preferably, a signal generating unit that can generate an out-of-jetting micro-vibrating signal as a periodical signal having a predetermined waveform is provided; the out-of-jetting micro-vibrating controlling unit is adapted to cause the micro-vibrating unit to operate based on the out-of-jetting micro-vibrating signal; a measuring unit that can measure a continuous operating time of the micro-vibrating unit by the out-of-jetting micro-vibrating controlling unit is provided; a standard-time storing unit that stores a predetermined standard time is provided; and a signal-generating controlling unit that can compare the continuous operating time and the standard time, and that can cause the signal generating unit to change the out-of-jetting micro-vibrating signal based on result of the comparison is provided.
In the case, dependently on the continuous operating time of the micro-vibrating unit, for example, strength of the out-of-jetting micro-vibrating operation can be lowered, so that deterioration of the micro-vibrating unit can be restrained.
In a concrete example, for example, the signal-generating controlling unit may be adapted to cause the signal generating unit to change the out-of-jetting micro-vibrating signal in such a manner that a frequency of the out-of-jetting micro-vibrating signal is lowered when the continuous operating time becomes longer than the standard time. Alternatively, the signal-generating controlling unit may be adapted to cause the signal generating unit to change the out-of-jetting micro-vibrating signal in such a manner that an amplitude of the out-of-jetting micro-vibrating signal is lowered when the continuous operating time becomes longer than the standard time.
After the frequency of the out-of-jetting micro-vibrating signal has been lowered by the signal generating unit, preferably, the signal-generating controlling unit is adapted to cause the signal generating unit to change again the out-of-jetting micro-vibrating signal before a liquid-jetting operation in such a manner that the frequency of the out-of-jetting micro-vibrating signal is returned to an original frequency. In addition, after the frequency of the out-of-jetting micro-vibrating signal has been returned to the original frequency by the signal generating unit, preferably, the out-of-jetting micro-vibrating controlling unit is adapted to cause the micro-vibrating unit to operate based on the out-of-jetting micro-vibrating signal for a predetermined time before the liquid-jetting operation.
Similarly, after the amplitude of the out-of-jetting micro-vibrating signal has been lowered by the signal generating unit, preferably, the signal-generating controlling unit is adapted to cause the signal generating unit to change again the out-of-jetting micro-vibrating signal before a liquid-jetting operation in such a manner that the amplitude of the out-of-jetting micro-vibrating signal is returned to an original amplitude. In addition, after the amplitude of the out-of-jetting micro-vibrating signal has been returned to the original amplitude by the signal generating unit, preferably, the out-of-jetting micro-vibrating controlling unit is adapted to cause the micro-vibrating unit to operate based on the out-of-jetting micro-vibrating signal for a predetermined time before the liquid-jetting operation.
In addition, in general, a capping mechanism that can seal the nozzle may be provided in a relative movable (scanning) area of the head member. In the case, preferably, the out-of-jetting micro-vibrating controlling unit is adapted to cause the micro-vibrating unit to operate during at least a part of time for which the capping mechanism seals the nozzle.
More preferably, the out-of-jetting micro-vibrating controlling unit is adapted to repeat a controlling step of causing the micro-vibrating unit to operate for a first constant time and causing the micro-vibrating unit not to operate for a second constant time while the capping mechanism seals the nozzle.
In the case, further preferably, a history recording unit that records history information about liquid-jetting operations is provided, and a time-changing unit that can change at least one of the first constant time and the second constant time based on the history information about liquid-jetting operations recorded by the history recording unit is provided.
Alternatively, further preferably, an environmental-information obtaining unit that can obtain environmental information around the capping mechanism is provided, and a time-changing unit that can change at least one of the first constant time and the second constant time based on the environmental information obtained by the environmental-information obtaining unit is provided.
In addition, in order to prevent deterioration of the micro-vibrating unit, it is preferable that the signal-generating controlling unit is adapted to cause the signal generating unit to change the out-of-jetting micro-vibrating signal in such a manner that a frequency of the out-of-jetting micro-vibrating signal is lowered while the capping mechanism seals the nozzle. Alternatively, it is preferable that the signal-generating controlling unit is adapted to cause the signal generating unit to change the out-of-jetting micro-vibrating signal in such a manner that an amplitude of the out-of-jetting micro-vibrating signal is lowered while the capping mechanism seals the nozzle.
In addition, the invention is a controlling unit that can control a liquid jetting apparatus including: a head member having a nozzle; a supporting member that can support a medium onto which liquid is to be jetted; a scanning mechanism that can cause the head member to relatively move with respect to the medium; a liquid jetting unit that can jet liquid from the nozzle; a micro-vibrating unit that can cause liquid in the nozzle to minutely vibrate; and a scanning-position-information outputting unit capable of outputting head-position information that represents a relative position of the head member while the head member is caused to relatively move by the scanning mechanism;
the controlling unit comprising: an area storing unit that stores a relative area to which liquid can be jetted from the nozzle while the head member is caused to relatively move by the scanning mechanism; an out-of-jetting micro-vibrating-area setting unit that can set out-of-jetting micro-vibrating areas before and after the relative area to which liquid can be jetted from the nozzle, based on the relative area to which liquid can be jetted from the nozzle; and an out-of-jetting micro-vibrating controlling unit that can cause the micro-vibrating unit to operate when the head member is located in the out-of-jetting micro-vibrating areas, while the head member is caused to relatively move by the scanning mechanism, based on the out-of-jetting micro-vibrating areas and the head-position information.
In addition, the invention is a controlling unit that can control a liquid jetting apparatus including: a head member having a nozzle; a supporting member that can support a medium onto which liquid is to be jetted; a scanning mechanism that can cause the head member to relatively move with respect to the medium; a liquid jetting unit that can jet liquid from the nozzle; a micro-vibrating unit that can cause liquid in the nozzle to minutely vibrate; and a scanning-position-information outputting unit capable of outputting head-position information that represents a relative position of the head member while the head member is caused to relatively move by the scanning mechanism;
the controlling unit comprising: an out-of-jetting micro-vibrating-area setting unit that can set out-of-jetting micro-vibrating areas before and after a liquid-jetting area to which liquid is to be jetted from the nozzle while the head member is caused to relatively move by the scanning mechanism, based on jetting data; and an out-of-jetting micro-vibrating controlling unit that can cause the micro-vibrating unit to operate when the head member is located in the out-of-jetting micro-vibrating areas, while the head member is caused to relatively move by the scanning mechanism, based on the out-of-jetting micro-vibrating areas and the head-position information.
A computer system can materialize the controlling unit or any element of the controlling unit.
This invention includes a storage unit capable of being read by a computer, storing a program for materializing the controlling unit or the element in a computer system.
This invention also includes the program itself for materializing the controlling unit or the element in the computer system.
The storage unit may be not only a substantial object such as a floppy disk or the like, but also a network for transmitting various signals.